FCE ASM 2016

Carbon cycling Cross-Cutting Theme

WORKING GROUP PARTICIPANTS: All the members of the Primary production, biogeochemical cycling and organic

matter dynamics working groups (including SPOM work), with special acknowledgement of the synthesis work led by Tiffany

Troxler and Jordan Barr

CENTRAL QUESTIONS

Reminder of the central questions of the working group

GOAL II (Carbon): Determine how the balance of fresh and marine water supplies to the oligohaline ecotone, by influencing P availability, water residence time, and salinity will control the rates and pathways of C sequestration, storage, and export.

GENERAL QUESTION 6: How do changing freshwater inflows, tidal and storm cycles, and climate patterns affect the magnitude, rates, and pathways of C sequestration, loss, storage, and transport across the land-water continuum?

NSF REVIEW FEEDBACK AND REFLECTION

Recommendation: Recognizing that a great deal of excellent work on carbon and organic matter decomposition dynamics is underway at the FCE-LTER, we recommend presenting this work to reviewers in an integrated, synthetic framework that links scales ranging from microbes to land and seascapes. It is not clear that the FCE-LTER has thought about the carbon research from this perspective (this comment extends to the discussion of data-model integration above). The panel recommends adding observations on redox chemistry and microbial community dynamics in order to elucidate the mechanisms that drive methane emissions, peat collapse, plant production and other soil-related processes.

GENERAL WORKING GROUP PROGRESS

One or two key new (post-review) results from working group that pertain to the central

questions and/or review feedback

A Bunch of ------------------

Synthesis!!!

Troxler et al 2015 Oceanography

Image on left: Flow is restored beneath the 1-mile bridge at the Tamiami Trail along the northeast boundary of the Park, May 2013. Project cost: $93 million USD. Everglades science helped inform the cost benefits of this project and a proposed additional 2.6 mile bridge.

Florida Coastal Everglades carbon cycle research

Florida Coastal Everglades carbon cycle research

Barr et al 2015 Eos

Tidal wetland focus

!  Spatio-temporal integration of –NEE, C burial, and change in C stocks !  Continuous monitoring of DIC and DOC IN and OUT of coastal rivers !  Surveys of pulses following disturbances !  Link remote sensing and ecosystem models to GPP, RE, and -NEE

Alkalinity

CO2 from calcification

Inter-group: Synthesis of Carbon and Trophic Dynamics working groups: Atwood et al 2015 Nature Climate Change

Does Increased nutrient supply influence ecosystem C storage in our oligotrophic systems? •  Increased production •  Increased decomposition

SHORT TERM (5 year) EXPERIMENTS Armitage and Fourqurean 2016 Biogeosciences

Does Increased nutrient supply influence ecosystem C storage in our oligotrophic systems? •  Increased production •  Increased decomposition

Howard, Lopes, Perez and Fourqurean in press ECSS

LONG-TERM (30 y) EXPERIMENTS

Net ecosystem exchange (-NEE) at two marsh sites: Shark River and Taylor Sloughs

Net ecosystem exchange (-NEE) at mangrove forest site SRS6

Some leaf-litter carbon enters the estuary and is exported as DIC, DOC, and POC There is some decoupling between –NEE and leaf-litter Disturbance events influence seasonal leaf-litter C patterns

NECB ≈ Soil C accretion (decades or longer) NECB / -NEE = (225 / 1016) = 22% ! 78% of C is exported

Annual carbon budgets in mangrove forests

“While changes in ecosystem structure, species composition, and disturbance regimes were beyond the scope of this research, results do indicate that climate change will produce small changes in CO2 dynamics in Everglades freshwater marsh ecosystems and suggest that the hydrologic regime and oligotrophic conditions of Everglades freshwater marshes lowers the ecosystem sensitivity to climate change.”

Malone et al 2015 Ecosphere

Observed (solid) versus modeled (hollow) CO2 exchange rates (NEE, Reco and GEE) at TS (A) and SRS (B). Atmospheric convention is used here and positive numbers

indicate a loss of C to the atmosphere.

Scenarios

pCO2 T Rain

Aquatic Carbon Export - Shark RiverDavid Ho, University of Hawaii

• Con$nuous  measurements  of:  •  Dissolved  inorganic  carbon  •  Dissolved  organic  carbon  • Water  residence  $me  

•  Gas  transfer  velocity  

•  To  derive:  •  Con$nuous  record  of  lateral  DIC  and  DOC  export  from  Shark  River  into  Gulf  of  Mexico    

•  Con$nuous  record  of  air-­‐water  CO2  fluxes  in  Shark  River  (example  next  slide)  

pCO2

k(600)

F(CO2)

(Zhang et al, 2014)

Production of primary producers other than seagrasses in Florida Bay

Sweatman and Collado-Vides

CO2 (aq)

CO2 (atm)

Organic C Carbonates

Alkalinity

Discussion point

Back of the envelop calculations: Over millennia, Florida Bay has had a net flux of ca. 2 gC m-2 month-1 to the atmosphere as a result of calcification, but only ca. 0.6 gC m2 month-1 uptake from the atmosphere for long-term NPP

Recommendation: Recognizing that a great deal of excellent work on carbon and organic matter decomposition dynamics is underway at the FCE-LTER, we recommend presenting this work to reviewers in an integrated, synthetic framework that links scales ranging from microbes to land and seascapes. It is not clear that the FCE-LTER has thought about the carbon research from this perspective (this comment extends to the discussion of data-model integration above). The panel recommends adding observations on redox chemistry and microbial community dynamics in order to elucidate the mechanisms that drive methane emissions, peat collapse, plant production and other soil-related processes.